Londoners stand on curb on Fleet Street, Thursday, as they observe two minute moment of silence

Millions of people across Europe have marked the one-week anniversary of the London bombings with two minutes of silence for those killed and wounded.

Traffic stopped and Londoners lined the sidewalks to honor the victims of the bombings last week that killed more than 50 people and left hundreds wounded.

Queen Elizabeth stepped out of Buckingham Palace for the memorial, and Prime Minister Tony Blair joined emergency workers for the moment of silence at the garden of his Downing Street residence.

Similar tributes were held in towns and cities across Britain and elsewhere in Europe.

Among those participating was George Psaradakis, the driver of a double-decker bus that police say was blown apart by an apparent suicide bomber in what is described as an al-Qaida-style attack.

"I send my thoughts at this time to the families of the innocent victims, especially my fellow colleague whose daughter lost her life on my bus," he said. "In today's silence we remember them. With quiet dignity and respect we show our deep contempt for those who planted the bombs and those who masterminded them."

The London police commissioner, Ian Blair, confirmed in a briefing with foreign correspondents that the police believe all four of the bombers committed suicide in carrying out the attacks, though he says they did not need to die, but chose to.

He said the fight against al-Qaida is complicated because it is not a traditional terrorist organization that has demands that can be negotiated.

"In the past, the Bader-Meinhof, the Red Brigades, ETA, the IRA, have been bombing their way to the negotiating table," he said. "What we have got here, is a situation in which people are bombing the table."

At a subsequent news conference, police appealed for public information on the movements of Hasib Hussain, suspected of blowing up the bus, and they released a closed-circuit television image of him carrying a backpack that supposedly contained the bomb.

Police also identified Shahzad Tanweer as the suspected bomber of a subway train near the Aldgate station. Media reports have described the 22-year-old Tanweer as a mild mannered cricket fanatic.